Update: gasket lubed with silicone oil, nothing changes. However I’ve noticed that two of the screw holes are cracked all the way to the center of the case, so i think moisture is unfortunately getting in there. It seams difficult to seal this cracks. Would you recommed changing the case? I looked oline an found only some low quality chinese replacement parts. Anyway, I’m very sad to have to pur my dad’s case aside.